1. Field of the Invention
The present invention relates to an abrasive tool for grinding, dressing, shaping or the like and also relates to a method of producing the same.
2. Description of the Related Art
Grinding wheels, a kind of abrasive tool, including polycrystalline diamond grains or cubic boron nitride grains (CBN) (i.e., superabrasive grains) have been proposed, e.g., in U.S. Pat. No. 4,923,490. Conventionally, an electrodeposited superabrasive grinding wheel includes diamond grains or CBN grains electroplated thereon. The electroplating enables the grinding wheel to copy a mold profile in detail with high precision because the manufacturing process proceeds at a relatively low temperature compared with sintering. Therefore, an electroplated grinding wheel makes possible high precision grinding, especially for high hardness and complex workpieces, so as that the demand for such grinding wheels is rising.
However, the grinding wheel tends to have a high concentration of the superabrasive grains because the grains are densely fixed on the outer peripheral surface of the grinding wheel. The high concentration of the superabrasive grains works against the engagement between the grinding wheel and the workpiece so as to increase the grinding force.
Diamond dressers, another kind of abrasive tool, have been proposed, e.g., in Japanese Published Patent Applications (Tokukoushou) 62-47669 and 53-11112. Japanese Published Patent Application 62-47669 discloses a diamond dresser whose concentration of the diamond grains is regulated by glass beads and metal balls manually prearranged on a mold using an adhesive. The percentage of the area filled with the beads and the balls determines the concentration of the diamond grains. However, it is difficult to coordinate the size of the beads or the balls.
Japanese Published Patent Application 53-11112 discloses a diamond dresser having a plurality of spiral grooves on its surface to reduce the dressing force. However, the dressing force changes whenever the grooves pass through the surface of the workpiece, so that vibrations may occur.